In an image forming apparatus which is represented by a laser printer or a copying machine, a process cartridge which is attachable to and detachable from a main body (hereinafter, referred to as an “apparatus main body”) of the image forming apparatus is provided.
The process cartridge is a member which forms contents to be expressed by letters or figures and transfers the contents to a recording medium, such as a paper sheet. Therefore, in the process cartridge, the photoreceptor drum in which the transferred contents are formed is included, and various means for forming the contents to be transferred by acting on the photoreceptor drum are disposed together. Examples of these means include a developing roller unit, a charging roller unit, and means for performing cleaning.
The process cartridge attaches and detaches the same process cartridge to and from the apparatus main body for maintenance, or mounts a new process cartridge on the apparatus main body instead of disengaging an old process cartridge from the apparatus main body. Attaching and detaching the process cartridge in this manner is performed by users of the image forming apparatus themselves, and it is desirable to perform attaching and detaching as easily as possible.
Meanwhile, it is necessary that the photoreceptor drum included in the process cartridge is rotated around a shaft line during the operation thereof. Therefore, the photoreceptor drum is configured to be engaged with a driving shaft of the apparatus main body directly or via another member at least during the operation, to receive a rotating force from the driving shaft, and to rotate. Therefore, in order to attach and detach the process cartridge to and from the apparatus main body, it is necessary to release (disengage) the engagement between the driving shaft of the apparatus main body and the photoreceptor drum every time attaching and detaching occur, and to mount the process cartridge again.
Here, if it is possible to move the photoreceptor drum (process cartridge) in the shaft line direction of the driving shaft of the apparatus main body, and to attach and detach the photoreceptor drum, the above-described structure for attaching and detaching is relatively simple. However, from the viewpoint of reducing the image forming apparatus in size or ensuring an attachment and detachment space of the process cartridge, it is preferable to disengage the process cartridge from the apparatus main body to be pulled out in the direction which is different from the shaft line direction of the driving shaft, and to mount the process cartridge on the apparatus main body to be pushed from this direction.
In PTL 1, a technology in which the driving force from the apparatus main body side is transferred to the photoreceptor drum when a cover of the apparatus main body is closed, and movement to be separated is performed so that the driving force is not transferred to the photoreceptor drum when the cover is opened, is disclosed. Accordingly, the process cartridge can be attached to and detached from the apparatus main body in the direction which is different from the shaft line direction of the driving shaft.
In addition, in PTL 2, an invention in which the driving shaft of the apparatus main body and the photoreceptor drum are engaged with each other via a rotating force transmission component having a trunnion structure attached to the photoreceptor drum, and the photoreceptor drum is rotated, is disclosed. Since the rotating force transmission component can change an angle with respect to the shaft line of the photoreceptor drum by the trunnion structure, engagement and disengagement between the driving shaft of the apparatus main body and the photoreceptor drum unit is easy.
In NPL 1, a technology in which a bearing member of the photoreceptor drum unit engaged with the driving shaft is provided to be movable in the shaft line direction by an elastic member, such as a spring, is disclosed. Accordingly, while the bearing member is biased by the elastic member when attaching and detaching the bearing member and the driving shaft, the attachment and the detachment are smoothly performed by moving and retreating in the shaft line direction.